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By R. K. Zipf

Recent scientific studies by researchers at the National Institute for Occupational Safety and Health (NIOSH) and the U.S. Army Corps of Engineers (USACE) presented the worst-case explosion pressures that can develop if a methane-air mixture of a certain composition and dimension accumulates and ignites within a sealed area of a mine. The Mine Safety and Health Administration (MSHA) issued its final rule on sealing of abandoned areas which considers potential explosion pressures and the risk of achieving the necessary conditions. The new MSHA seals regulation has increased the pressure design criteria an order of magnitude beyond the old standard of 140 kPa (20 psi) to 800 kPa (120 psi). However, there still are major knowledge gaps pertaining to seals and sealed areas including: (1) the composition of the sealed area atmosphere and how it changes in time and space, (2) explosion pressures that might actually develop within sealed areas, (3) engineering procedures to follow when designing seals and seal installations, and (4) guidelines to manage the atmosphere within sealed areas with monitoring or inertization. NIOSH has initiated a seals research program with collaborators from Safety in Mines Testing and Research Station (SIMTARS) in Australia, West Virginia University (WVU), the Naval Research Laboratory (NRL), and USACE. Highlights of progress so far include: (1) construction of a gas explosion tube at Lake Lynn Laboratory for studying large methane-air explosions, (2) computer simulation of the fluid dynamics of high pressure methane-air explosions, (3) development of seal analysis methods considering construction materials, reinforcement and the seal foundation, and (4) development and testing of innovative seal designs that utilize inexpensive, readily-available rock rubble to resist high explosion pressures. NIOSH researchers aim to provide sound engineering guidelines to better address the new MSHA seal regulations. DISCLAIMER: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By cheng Peng-fei, TANG Hai-yan, guo Xiao-chen, LI Jing-she, Liang Yong-cang, Zhao Baojun

In the process of oxygen blast furnace, the lower coke ratio and the higher coke load make the skeleton coke more important. To understand the dissolution of coke in melting and dropping zone, the influence of FeO content, temperature and reaction time on the dissolution of coke with slag were studied by single-factor experiment. Meanwhile, the three factors and three levels orthogonal were conducted. The dissolution degrees were characterized by the weight loss ratio and diameter variation. The results showed that the weight loss ratio increased and the diameter decreased with the increase of FeO content, temperature and time. The three factors and three levels orthogonal test showed that time was the most significant factor on coke dissolution, FeO content of the second, and finally the temperature. The microstructure of coke after reaction indicated that the dissolution occurred on coke surface.

Jan 1, 2016

By Maike Von Heymann, Sergio González, Gaelle Dupuis, Ignacio Ishizawa, Claudia Toledo

Anglo American es una compañía minera global líder que cuenta con productos componentes esenciales en casi todos los aspectos de la vida moderna. Nuestro portafolio de operaciones competitivas de primera clase, con una amplia gama de futuras opciones de desarrollo, proporciona muchos de los metales y minerales esenciales para un mundo más limpio, ecológico y sostenible, y que cumpla con las demandas diarias de los consumidores. Como parte de la implementación de nuestro plan de minería sostenible impulsamos la implementación de las plataformas de desarrollo colaborativo, que en el caso de Moquegua se denomina Moquegua Crece.

Sep 29, 2023

By Ronald Thomas

The scope of this paper is to examine the growth of safety in an individual and offer new goals in that development. The paper will examine the individual's natural growth and show how it parallels the individual in a safety environment. An individual's new goals for safety include more than the standard accident-free conditions. The new goal strives for a safer working environment where unsafe acts are eliminated through independent knowledge and an individual's growth of interdependency in safety related areas of concern. It will explain how this goal cannot be reached unless driven from the top down in an organization but empowered from the bottom up. Various reference or support organizations will be covered. These organizations deal with safety in mining and explosive use of manufacturing. Other support organizations exist but since this paper is "Back to Basics" only a few major groups will be covered.

Jan 1, 2001

By E. Van Der Lingen

This paper provides a review on coloured gold, platinum, andpalladium intermetallic compounds, and discusses the models thatwere developed to obtain these materials. These compounds have acrystal structure of high symmetry, such as the CaF2or CsClstructures, ensuring distinct electron band structures. Variousexamples of coloured gold, platinum, and palladium intermetalliccompounds are provided. More in-depth discussion is provided on thepurple gold (AuAl2) and yellow platinum-aluminium (PtAl2)compounds with CaF2structure, as well as the purplish-pinkpalladium-indium (PdIn) compound with CsCl structure. Precious metal intermetallic compounds are used in jewellery andprovide a new dimension to design. Some of these compounds havealso found use as barrier coatings on turbine blades for jet engines,and more recently, research has been conducted into their potentialuse as catalysts, electro-catalysts, sensors, capacitors, and fordecorative coatings.

Jan 1, 2014

By W. J. Weymark

"The Gregg River project is located 40 kilometres southwest of Hinton, Alberta, adjacent to and east of Jasper National Park. This metallurgical coal mine has been developed as a joint venture between Gregg River Coal Ltd. (a subsidiary company of Mana/ta Coal Ltd.) and seven Japanese companies. This 200-million dollar project consists of a conventional truckshovel open-pit operation and a coal preparation plant rated at 2.14 million tonnes of clean coal per year. Mining operations started in October 1982 with plant start-up following in April 1983. Introduction This paper is an overview and update of the Gregg River project, a metallurgical coal mine being developed as a joint venture between Gregg River Coal Ltd. (a subsidiary of Manalta Coal Ltd.) and seven Japanese companies. The Gregg River Coal leases cover 3440 hectares and are located 40 kilometres south of Hinton, Alberta, adjacent to and north of Cardinal River Coal Mine (Fig. 1). This 200-million dollar project consists of a conventional truck-shovel operation and a coal preparation plant rated at 2.14 million tonnes of clean coal per year. A total of 31.5 million tonnes of clean metallurgical coal will be sold to the Japanese over a fifteen-year term. At present, mining operations are ahead of schedule and the plant started up on schedule in April 1983. Access and Climate An all-weather road, Highway 40, connects the minesite with Hinton (the nearest commercial centre) and a Canadian National Railway (C.N.R.) spur line connects the minesite with the C.N.R. main line in Edson. Hinton is accessible by road chartered airline and rail. ' ~h~ rug~ed and varied topography in the area creates large vanations m temperature and precipitation over short distances. The region is characterized by precipitation throughout the year long cold winters and short cool summers. The mean temperatur~ of the area range from a low of -14°C in January, the coldest month, to a high of 12°C in July, the warmest month. Long-term precipitation data indicates a mean yearly precipitation of 870 mm of which 620Jo occurs during the summer months."

Jan 1, 1985

A laboratory size solvent extraction apparatus has been constructed, which incorp- orates three stages of countercurrent extraction, followed by two stages of counter- current stripping. The model uses a gravity flow system from one stage to another and air lift pumps to recirculate organic and aqueous phases. A novel pump/mixer system is used to transfer solutions from the mixer compartments to the settler compartments. The model has proven valuable in the teaching of solvent extraction principles.

Jan 1, 1999

By P Jere

Mechanically coupled rock bolts encapsulated in cementitious or polyester cartridge resin grouts have been widely adopted for various underground rock reinforcement applications. Resin grouts are considered a superior product, however, both systems have their advantages and limitations, with the relative performance, quality installation cost and cycle time as the most notable parameters. Both applications have optimal rock bolt combinations and preferred ground conditions. Cementitious grouts are favourable for use with secondary deep embedment anchors. These are installed using various equipment with a series of autonomous tasks required to complete the installation cycle. The cartridge resin system can be utilised by a bolting or face boring rock drill to complete the full support installation cycle. This reduction in equipment changeouts mid-cycle generally deems it the more practical application and popular choice for primary support. Self-drilling anchors (SDAs) and hollow bolts have been a viable alternative to traditional rock reinforcement in variable and challenging ground conditions. Using a pumpable post installation grouting system, SDAs have proven to aid the quality of installation, but due to the additional equipment and cycle steps associated with application, the cycle time is increased. In recent years, fully mechanised bolting equipment designed to utilise a combination of self-drilling anchors and a thixotropic pumpable resin installed in a single pass has entered the market. This innovation is anticipated to deliver the advantages described above, with fewer limitations, and significantly improved development and rehabilitation rates. St Barbara Mining and Byrnecut Australia, supported by Master Builders Solutions, were first to conduct extensive trials and implement this rock bolting approach in an Australian hard rock underground mine and record the actual performance.

Mar 29, 2023

By Laurance S. Reid, Joe A. Porter

Gas dehydration plays an important part in the production of natural gas. Effective dehydration prevents formation of gas hydrates and the accumulation of water in transmission Systems,2,6,7 insuring uninterrupted gas deliveries at maximum efficiency under the most adverse weather conditions. At the present time, most gas companies require a maximum water vapor content of seven lb per million standard cu ft of gas. so that virtually all gas tendered for sale must he dehydrated to meet this specification. For a number of years it has been common practice to produce gas and gather it at a common point for dehydration prior to discharge into the transmission system.1,3,11,16,17 However, higher transmission line pressures, long gathering lines and relatively low ground temperatures have made it necessary to dehydrate gas at. or near. individual. wells in order to gather gas from a number of newly developed fields without unusual difficulty. Where gas has been dehydrated at pressures ranging from 300 to 800 psi in the past. future trends indicate that these processes may be operated at pressures as high as 2,000 psi. Economics of gas dehydration are of great importance, partitularly where facilities must he provided to process relatively small quantities of gas, such as the production from an individual well. Although the adsorption of water vapor from gas on a granular sorbent material such as activated bauxite, activated alumina, or one of the alumina-silica gels is highly effective and produces virtually "bone dry" gas, the cost of a small unit of this type is substantially greater than that of an absorption process which, through proper selection of the absorbing liquid, will dehydrate the gas sufficiently to meet pipe line specifications. For this reason, a great deal of emphacis has been placed on the development of small, inexpensive dehydration units8,24 and the search for more effective absorb. ent liquids has been intensified. A wide variety of methods for dehydrating gas are known' and many of these have been used in industry. Earlier applications of the absorption process employed concentrated solutions of calcium and lithium chlorides as the absorbent. The severe corrosion problems inherent in handling these solutions and the relatively small dew point depressions obtained caused early abandonment in favor of, or conversion to. diethylene glycol when it was found that aqueous solutions of this organic liquid were more hygroscopic than the brines and were non-corrosive. Processes employing diethylene glycol-water solutions are widely used for gas dehydration at pressures ranging as high as 1,200 psi.13,14,15 At nominal pressures a dew point depression of 45° to 50°F may be be and the data of Russell et al." indicate that a minimum dew point is obtained from the effluent gas at a pressure of approximately 1,200 psi when the gas is in equilibrium contact with a 95 per cent by weight diethylene glycol solution. In a number of instances the dew point depression obtained with diethylene glycol-water solutions is not sufficient to produce a specification product without cooling the inlet gas. In a recent search for a better absorhent, triethylene glycol was used in a small commercial dehydration unit and subjected to rather exhaustive field tests.' The data obtained were encouraging and indicated that, at pressures ranging from 300 to 500 psi, triethylene glycol porduced a substantially greater dew point depression than diethylene glycol. These results led to an investigation of the system natural gas-water-triethylene glycol in an effort to obtain vapor-liquid equilibrium data, to determine pressure limitations, and to develop other data pertinent to the design of gas dehydration processes. A review of the literature has failed to reveal any data which permit reasonably accurate calculation of the vapor-liquid equilibrium conditions for a solution of water and triethylene glycol in contact with natural gas at high pressure. Since these constituents form a non-ideal system, the Poynting equation18,21 or the usual combination of Raoult's and Dalton's laws19,20,22 would not be valid. Correction of Raoult's and Dalton's laws by the use of activity coefficients2' is not feasible for available data are insufficient for the prediction of the actual increase in the ratio of the activity of one component in the vapor phase to its activity in the liquid. Therefore. experi-

Jan 1, 1950

By M. J. Russell, W. E. Stephens, D. B. Mohamad, A. B. MacKenzie

Redox front processes in rocks are important in the context of both radioactive waste disposal and the development of orebodies. Results are presented from a study of the distribution of uranium and thorium and the natural decay series equilibrium about redox fronts in a granite at the Criffel pluton and Craignair quarry, Dalbeattie in southwest Scotland. The results are considered in the context of large scale uranium aqueous transport in the region and compared with those from a previous study of highly developed redox fronts at Pocos de Caldas, Brazil. Results show that the Criffel pluton has experienced a recent and rapid removal of uranium from the uppermost section of the granite whereas thorium has remained relatively immobile. The radium and uranium distributions indicate that diffusion processes probably control the distribution of radionuclides about the front. These processes are similar to those observed at Pocos de Caldas. The trends of concentration and activity ratio about the Dalbeattie redox front are less pronounced than those at Pocos de Caldas owing to the shorter time available for the process and the lower intensity of weathering at Dalbeattie.

Jan 12, 1992

By T. P. Meloy

A methodology is presented for the spreadsheet solution of processing networks performing separations with the methodology developed here a spreadsheet grid is used to represent networks with and without recycle loops. In this manner, network solutions are numerically approximated by spreadsheet grid solutions. The methodology was used to explore the ramification networks developed by the Chinese for tungsten and molybdenum processing. Non-linear stage transfer functions for two-component sharp separations can be used.

Jan 1, 1994

By Hatch, A. Reple, W Valery

The mining industry is facing declining feed grades which require the mining and processing of larger volumes of material per tonne of product. Pre-concentration aims to remove barren material at as coarse a particle size and as early in the process as possible to reduce processing costs, energy consumption, water losses, and greenhouse gas emissions while increasing production and profitability. This may be achieved using bulk ore sorting—the separation of barren gangue from a fully loaded conveyor belt based on the grade as measured or inferred from a sensor. This paper evaluates the technical and economic viability of bulk ore sorting for the PanAust Phu Kham copper deposit in Lao PDR. Bulk ore sorting technology is described briefly along with discussion of appropriate sensor and diversion systems for the Phu Kham operation. To evaluate the economic implications, the actual mined material and costs from 2014 were used as the base-case. Sampling data was not available; therefore, the ore grade variability that would feed a bulk ore sorter was estimated using geo-statistical tools based on mine grade control data. The sorter performance when treating this material was simulated considering the accuracy of the sensor measurement and errors associated with material diversion. The impact on inferred cash flow was estimated for several different scenarios considering the additional costs for sorter operation and reject handling. The evaluation demonstrated that bulk ore sorting at Phu Kham has the potential to increase the amount of metal in product and/or reduce processing plant throughput (and costs) to improve the annual inferred cash flow for the conditions investigated. The sorter is the gatekeeper – only material above the cut-off grade (value-adding) reports to the processing plant; no waste dilutes the feed. Likewise, above cutoff grade material is not lost to waste; preventing lost revenue.

Jan 1, 2016

"Only the coal of the Sunnyside district in Carbon County is coked. Two companies, the Utah Fuel Company and the Columbia Steel Corporation, operating adjoining mines at Sunnyside and Columbia, produce coke.The Utah Fuel Company has 819 beehive coke ovens at Sunnyside. Only 350 ovens are being operated at the present time, largely because the smelters which had been using Sunnyside coke changed their equipment from blast furnaces to reverberatory furnaces.The Columbia Steel Corporation operates a plant of 33 Koppers type by-product coke ovens at Ironton, near Provo. About 800 tons of coal are used per day to produce coke for the company's iron blast furnace plant pie ovens produce about 400 tons of coke, 12,000,000 cubic feet of gas, 9,000 gallons of coal tar, 3,000 gallons of benzol and several tons of ammonia sulphate per day.The total coke production for the State from the earliest output of record in 1880 until June 30, 1924, is 5,947,714 tons."

Jan 1, 1925

Computer applications in mine 'production' planning and control are concerned with the here and now. In production planning and control we are dealing with tactics as opposed to strategy. Our objective is to make the best of the situation in the short term, i.e., in a relatively fixed environment with relatively fixed plant, equipment, and labor. Environmental factors include not only the geology of the deposit but also market factors (such as price) and governmental constraints and regulations. Mine production planning systems are applied at the interface between concept and execution. Mine production control systems are applied at the interface between execution and revised operating practices or a revised concept. Fig. 1 shows the information flow that takes place regardless of whether the planning and control systems are manual or automatic. The feedback that results depends on the feedback mechanism that has been established, and this feedback can be enhanced by careful systems analysis and design. Chronologically, production planning and control activities support the last in the series of line functions that are ordinarily performed by mining companies. The first of these is exploration, the second is evaluation and development, and the third and final function is production.

Jan 1, 1979

By Louise H. Michaud

Albian Sands Energy is scheduled to begin production at its oilsands operations in the fall of 2002. Start-up includes the selection and implementation of over 75 IT systems or computer applications. These include engineering applications, systems required to control mining activities, maintenance, the processing plant and utilities, and also systems required to run the company, such as human resources, finances and inventory/warehousing. This paper outlines the processes used for the selection, implementation and integration of these systems in order to optimize the use of information and to meet the technical, business and IT requirements of the company. The first step in Albian?s approach to identifying system requirements is the development of a Business Activity Model, outlining all tasks involved in running the operations. The computer applications required to accomplish each task are then identified by having the IT team work closely with each technical and business unit. Historically, at some companies, the selection of systems has been lead by the IT team or by consultants, with little input from the technical or business units. Typically, this results in products that don?t meet the company?s expectations. To ensure a more positive outcome, Albian believes that it is imperative that the company?s technical and business people are closely involved in the selection process. Integration of the IT systems is also key, including linking all applications through a Data Warehouse and EDMS. Over 120 required integrations have been identified. This ensures the storage of all data in only one location, data security, and easy data and document retrieval for all requirements throughout the company.

May 1, 2002

By C. F. Hews, P. N. Calder

"MIROC and The Mining Industry The Mining Industry Research Organization of Canada (MIROC), incorporated in 1975, is a non-profit organization sponsored by member companies from within the Canadian mining industry. The Canadian mining industry is a world leader in technological development and in organizational and human resources development. A prime objective within the industry is to retain this leadership and also improve its competitive position worldwide.MIROC is dedicated to support the objectives of its member companies and their common interest, and the objectives of the industry. In this context: MIROC's mission is to encourage the formulation of ideas to improve mining technology and methods by any source, and to foster the development and testing of promising initiatives in progressive steps from the early stages of conceptual and feasibility research through manufacture to delivery of new technology to the mining industry. In so doing MIROC plays an important role in the development of individuals skilled in mining research. Management ApproachMIROC's research program is driven by member companies who have interests throughout Canada. The board of directors approve projects that are acceptable to its members. While MIROC's basic research funding is provided by its member companies, about 30% of its annual research budget is now derived from royalties generated from previous research activities."

Jan 1, 1994

By Johnson D. P, Beamish B. B

The northern Bowen Basin has a very large resource of coalseam methane gas-in-place - 136 TCF(7ohnson and White, 1988). The gas is pipeline quality, being 98-99 per cent methane with traces of carbon dioxide and higher hydrocarbons. The largest resource of natural gas within the coalseams of the northern Bowen Basin is contained in the Moranbah Coal Measures (75 per cent). The next most important resource is in the combined upper Fort Cooper (16 per cent) and Rangal (nine per cent) Coal Measures. The far northern parts of the basin have low gas contents due to the combined effects of limited extent of the coal measures, shallow depth and low rank. Reserves per well are more than double that of the best coalseam methane wells in any basin in the United States. In some areas of the Moranbah Coal Measures, the gas-in-place estimates exceed 225 million cubic metres per well (80-acre spacing). A distinction is made between resource base, as determined from this basin assessment, and the deliverability potential. Parameters used to estimate gas-in-place (coal area, thickness, density, rank and depth) can be adequately extrapolated from areas of high- to low- data density. Parameters affecting methane production (permeability, gas depletion factor and critical desorption pressure) cannot be generalised. Exploration and development programs must rapidly develop a predictive capability for these factors, on a local scale, through geological modelling and confirmation drilling.

Jan 1, 1991

There is a significant amount of historical mining and exploration information available. This information is often distributed throughout a number of reports or plans, available from a variety of sources, and in many differing formats. The ability to capture paper-based historical information in a modem digital format provides mining and exploration companies with valuable information that can be used in a number of ways; for example, reassessments of exploration or mining work previously undertaken, or used in conjunction with current exploration information.   The purpose of this paper is threefold. Firstly, to present the paper-based historical information; highlighting some of the problems encountered, solutions to those problems, and any assumptions used. Secondly, to present the historical data in digital format, and demonstrate the tools available to analyse geological and associated information, and finally, to illustrate some of the potential future applications of the information, including mining optimisation, mine design and scheduling.   The Glenorchy scheelite/gold prospect has been used as an example. Within the overall prospect two smaller areas were selected. The Mount McIntosh and surrounding areas, focuses on exploration and surface excavation information. The Mount Judah area (State and Kelly-Taylor workings) focuses on underground mining and exploration information.  

Jan 1, 2001

THE alkaline method for the estimation of zinc cannot, in the writer's opinion, be relied. upon to within very narrow limits between two assayers on unknown quantities of zinc. The end point is not decisive enough, and allows the personal factor toenter largely into the assay. The following investigation was undertaken to see how accurate the acid method is on Broken Hill concentrates and ores, and what should be the limit between the results of two assayers. The method adopted is as follows:Weigh sufficient amount of ore to give titration (between 20 and 50 cc.), place in tall 400 cc. beaker, cover, add 7 cc. nitric acid and heat till brown fumes cease to be evolved. Wash dock glass into assay, add potassium chlorate, evaporate to dryness on a slow fire with the beaker uncovered. When no smell of chlorine or nitric acid is observed, remove and cool. Add 100 cc. boiling water, then 7 grm. ammonium chloride, W cc. ammonia (.880 sp. gr.), boil for five minutes, filter, wash...

Jan 1, 1911

By H. V. Welch

In this paper, as prepared for delivery at the Southern California regional meeting on Oct. 14, 1948, it was thought best to interpret the term "economics" in a rather broad manner and to include, in addition to the material losses and recoveries and associated monetary values (Part I), a limited discussion of the increased difficulties or the particular problem and the special requirements, as the particle sizes of the suspended particles range down from the relatively coarse to 100, to 10, to 1 micron or even to a fraction of one micron (Part II). Further, it is not quite in order to overlook entirely the community and individual health problems, although space requires the economics of this to be considered only very incompletely. Therefore, Part III, covering this phase of the subject, is very limited. This paper, then, is divided into 5 parts or headings as follows: I Losses and/or values in suspended solids. II Particle size. III Dust and fumes in community and individual living. IV Means and Procedures for dust and fume collection. V Description or examples of specific equipment in service and of the several types used for dust and fume collection. Because of the wide extent and wealth of subject material available and the space and time limitation imposed, presentation and discussion are less than originally planned. I—Losses and/or Values in Suspended Solids The weight involved in moving streams of industrial plant gases is commonly not appreciated, neither is their carrying power in the weight of solids maintained in suspension and moved with the gas stream from a point of origin or pick-up to a point of dissipation or settlement. These, however, are major weight figures; for example, in a modern iron blast furnace there may be five tons of gas for every ton of iron produced and by the time this blast furnace gas has been burned in stoves or under boilers the weight of gas discharged to atmosphere is on the order of eight times the weight of iron produced. Similarly for nonferrous metallurgy there may readily be from 10 to 20 times the weight of gases discharged to atmosphere as there is metal produced. A cement kiln in operation or a kiln in service to produce metallurgical lime may have on the order of 5 to 6 times the weight of stack gases as of clinker or lime produced, and at least the cement kiln, because of the very fine nature of its feed, is a very heavy dust producer. It may be noted that there have been two developments in progress for nearly three decades. Both are extraordinary in the industrial economics effected and in their ready availability to ever larger units of operation and their ever widening importance in industry, and both are productive of great quantities of finely divided material in furnacing. The first of these is the flotation process for ores, especially the metallics such as copper, lead, and zinc; and the second, powdered fuel combustion for power plant, industrial plants and metallurgical operations. Today, new developments, for example, flotation for the nonmetallics such as higher grade limestone for cement manufacture which requires still finer grinding and the powdered-coal-fired boilers with production ratings of over 1,000,000 lb of steam per hr, bring still more concentrated and hugely increased quantities of stack emission. Perhaps the honors for the greatest interest in the quantities and values escaping in waste furnace and equipment gases belong to the nonferrous metallurgical operations. Their record of achievement in the installation of dust and fume collection equipment, largely baghouses or Cottrell electrical precipitators, is exceeded by no other industry. Something of the magnitude and variety of equipment utilized in such recovery systems was covered by the writer in two papers presented to the Institute some 10 years ago.1,2 It is not intended to repeat the material of those articles, but it is thought that they complement this offering and should be noted. COPPER ROASTERS As the copper roasters are the first of the series of furnaces handling the copper-bearing concentrates in the usual copper smelter of today, it is in order to make them the first consideration. Multiple hearth sulphide roasters, not hard driven, often maintain their dust loss through exit gases at 3 pet or below of feed to furnace; in hard-driven or maximum-driven furnaces, exit gas losses often approximate 7 pet of charge with a ±2 pet variation for special conditions prevailing at some plants. A 5 pet loss of feed in a roaster gas exit, unless reclaimed, often makes the difference between a profit and loss operation, and in many cases substantial recovery is the very basis of dividend payments. As there is available very practical and successful equipment for the collection of the

Jan 1, 1950